Polyester resins are well known in the art, where an alkyd ingredient is reacted with about 50 wt. % of a vinyl group-containing monomer, such as styrene, vinyl acetate or vinyl toluene, to provide a fast drying resin which may be diluted by addition of aromatic naphtha or other comparable solvent, as taught by Yetkon, in U.S. Pat. No. 3,743,615. Cummings, in U.S. Pat. No. 3,620,989, recognized that such copolymers are low molecular weight materials and films formed from them tend to be soft. In addition, the use of large amounts of solvents and vinyl monomers posed fire and ecology problems, providing compositions having flash points of about 26.degree. C to 32.degree. C.
Cummings attempted to solve these problems by using a water emulsion copolymer of gylcerol, soy oil, maleic anhydride, phthalic acid and ethylhexyl acrylate or vinyl acetate, where a large excess of maleic anhydride over phthalic acid was used. The Cummings resins, while having good thermal properties at about 135.degree. C to 160.degree. C, have high energy requirements, since they need a long baking period to remove all of the water.
What is needed is a non-aqueous polyester resin composition, having at least about 75% solids and good pot life, which is useful in 155.degree. C to 220.degree. C environments, and which quickly cures to a hard, tough insulation, with minimal solvent removal, energy requirement and fire hazard problems.